1. Field of the Invention
This invention relates in general to grain harvesting combines, and in particular to a rethreshing rotor for rethreshing tailings from the sieve section of a grain combine.
2. Description of the Prior Art
A grain harvesting combine has a header which cuts the crop and feeds it upward into a threshing rotor. The threshing rotor rotates within a perforated housing, passing grain within clearances between the threshing rotor and perforated housing to thresh grain from the crop. The threshed grain falls through the perforations onto a grain pan, and from the grain pan onto a set of upper and lower sieves. The sieves are oscillating, causing clean grain to fall through for collection. A blower blows air upward through the sieves, discharging chaff to the rear. Straw from the threshing chamber proceeds through a straw beater and out the rear of the combine.
The clean grain is collected and conveyed to the bin. Incompletely threshed grain will not proceed through the fingers of the sieves, yet is too heavy to be blown out the rear along with the chaff. This grain, called "tailings" or "returns" is often returned to the rotor for rethreshing. However, when tailings are returned to the rotor for rethreshing, under some grain conditions, called "white caps", tailings will pass through the rotor yet again without the grain separating from the chaff.
Some prior art grain harvesting combines have rethreshing rotors for receiving tailings from the sieves, rethreshing the tailings, and passing the tailings back through a primary rotor for rethreshing. However, these prior art tailings rethreshers typically have only a narrow width, and receive tailings from an auger which passes along an end of the sieves.